PURPOSE: To prepare a pesticide composition by dispersing a mineral acid salt of hydrazine and colloidal silica in water.

CONSTITUTION: A mineral acid salt of hydrazine (e.g. hydrochloride) and colloidal silica are dispersed in water to obtain a milk white liquid. The composition has strong reducing activity and rapid-acting effectivity, and is useful as a fungicide, insecticide, plant growth regulator, etc. It is especially effective to resistant pathogenic fungi and resistant insects.